Abstract

An experimental rheometric investigation is performed to assess the utility of various gelation point determination methodologies. Controlled shear stress and controlled shear rate methods are developed to investigate gelation processes in waxy oils. The nonoscillatory rheological method exhibits high reproducibility for model wax oils as well as for real crude oils. In addition, the nonoscillatory methods are in good agreement with standard oscillatory gel point determination methods. The effect of imposed shear stress, imposed shear rate, and cooling rate on gelation point is investigated with two types of model oils: 5 wt % macrocrystalline wax in Primol 352 and 5 wt % macrocrystalline wax in dodecane. In addition, the effect of wax content on gel temperature of macrocrystalline wax in dodecane is investigated. Moreover, the effect of additives (A3 and A4) on gelation point of a real crude oil UL-YS1 is investigated. Finally, the gelation temperatures of 5 wt % macrocrystalline wax in Primol 352, crude oil UL-YS1, and Se-7-E06 are investigated by three methods: constant imposed shear stress, constant imposed shear rate, and oscillatory G′–G″. Gel point results are obtained with the various protocols for real and model oil systems. The nonoscillatory rheological method is applicable for gel point determination of model wax oils as well as real crude oils. Hence, due to its high repeatability and instrumental accuracy, the nonoscillatory rheological method is a promising method for gel point determination.

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